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| United States Patent |
5,751,857
|
|
Kobayashi
|
May 12, 1998
|
Image processing method
Abstract
An image processor performs a processing method which includes (a) reading
out hierarchical-encoded binary image data stored in a storing medium, (b)
decoding the binary image data read out in the step (a), (c) performing a
multi-level generation to the binary image data decoded in the step (b),
and (d) causing a display device to display an image, on the basis of the
data decoded in the step (b) or the data multi-level generation processed
in the step (c), wherein, in a case of causing the display device to
display the image on the basis of data having a resolution which is higher
than the resolution of the display device, the image is displayed in the
step (d) after the binary image data is multi-level generation processed
in the step (c), thereby preventing deterioration of the image when the
image data stored in the storing medium is output.
| Inventors:
|
Kobayashi; Shigetada (Tokyo, JP)
|
| Assignee:
|
Canon Kaubshiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
576904 |
| Filed:
|
December 22, 1995 |
Foreign Application Priority Data
| Current U.S. Class: |
382/232; 341/56; 345/214; 345/619; 382/240 |
| Intern'l Class: |
G06K 009/36 |
| Field of Search: |
382/232,240
358/500,508
345/112,202,214
341/56
|
References Cited
U.S. Patent Documents
| 4742558 | May., 1988 | Ishibashi et al. | 382/240.
|
| 4858017 | Aug., 1989 | Torbey | 382/240.
|
| 5050230 | Sep., 1991 | Jones et al. | 382/240.
|
| 5140441 | Aug., 1992 | Sugiura et al. | 358/456.
|
| 5162925 | Nov., 1992 | Takaoka et al. | 358/447.
|
| 5521717 | May., 1996 | Maeda | 382/240.
|
| 5561536 | Oct., 1996 | Sugiura et al. | 358/500.
|
Primary Examiner: Couso; Jose L.
Assistant Examiner: Do; Anh Hong
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper & Scinto
Claims
What is claimed is:
1. An image processing method comprising the steps of:
(a) reading out hierarchically encoded binary image data stored in a
storage medium;
(b) sequentially decoding the binary image data read out in said step (a),
in the order of a low-resolution image to a high-resolution image;
(c) performing a multilevel generation to the binary image data decoded in
said step (b);
(d) causing a display device to display an image, on the basis of the image
data decoded in said step (b) or the image data multilevel-generation
processed in said step (c);
(e) judging whether or not a resolution of the image data decoded in said
step (b) is higher than a resolution of the display device in said step
(d) to display the image on the basis of the image data; and
(f) controlling said step (d) to cause the display device to display the
image based on the image data multilevel-generation processed in said step
(c) if YES in said step (e), and said step (d) to cause the display device
to display the image based on the binary image data decoded ins said step
(b) if NO in said step (e).
2. A method according to claim 1, wherein the hierarchical encoding in said
step (a) is an encoding in a JBIG system.
3. A method according to claim 1, wherein the image data stored in the
storing medium can be output at a resolution of a printer which is to be
used for printing out the image based on the image data.
4. An image processing method comprising the steps of:
(a) reading out hierarchically encoded binary image data stored in a
storage medium;
(b) sequentially decoding the binary image data read out in said step (a),
in the order of a low-resolution image to a high-resolution image;
(c) judging whether or not a resolution of the image decoded in said step
(b) exceeds a predetermined resolution;
(d) performing a multilevel generation to the binary image data decoded in
said step (b);
(e) causing a display device to display the image, on the basis of the
image data decoded in said step (b) or the image data
multilevel-generation processed in said step (d); and
(f) controlling said step (e) to cause the display device to display the
image based on the image data multilevel generation processed in said step
(d) if YES in said step (c), and said step (e) to cause the display device
to display the image based on the binary image data decoded in said step
(b) if NO in said step (c).
5. A method according to claim 4, wherein the hierarchical encoding in said
step (a) is an encoding in a JBIG system.
6. A method according to claim 4, wherein the image data stored in the
storing medium can be output at a resolution of a printer which is to be
used for printing out the image based on the image data.
7. An image processing method comprising the steps of:
(a) reading out hierarchically encoded binary image data stored in a
storage medium;
(b) sequentially decoding the binary image data read out in said step (a),
in the order of a low-resolution image to a high-resolution image;
(c) sequentially switching the image decoded in said step (b) to cause a
display device to display the switched image;
(d) inputting an interruption instruction of the image switching to be
displayed in said step (c);
(e) performing a multilevel generation to the binary image data decoded in
said step (b); and
(f) controlling, in accordance with input timing of the interruption
instruction in said step (d), the switching in said step (c) between the
operation of causing the display device to display the image based on the
binary image data decoded in said step (b) or the operation of causing the
display device to display the image based on the image data
multilevel-generation processed in said step (e).
8. A method according to claim 7, wherein the hierarchical encoding in said
step (a) is an encoding in a JBIG system.
9. A method according to claim 7, wherein the image data stored in the
storing medium can be output at a resolution of a printer which is to be
used for printing out the image based on the image data.
10. A method according to claim 7, wherein said step (e) further includes a
step of converting a resolution of the image data multilevel-generation
processed, in correspondence with a resolution of the display device, and
said step (c) causes the display device to perform the display in the
resolution converted in said step (e), in accordance with the control in
said step (f).
11. A method according to claim 7, further comprising a step of holding a
display state in case of inputting the interruption instruction in said
step (d).
12. A computer readable program, stored in a storage medium, for performing
an image processing method comprising the steps of:
(a) reading out hierarchically encoded binary image data stored in a
storage medium;
(b) sequentially decoding the binary image data read out in said step (a),
in the order of a low-resolution image to a high-resolution image;
(c) performing a multilevel generation to the binary image data decoded in
said step (b);
(d) causing a display device to display an image, on the basis of the image
data decoded in said step (b) or the image data multilevel-generation
processed in said step (c);
(e) judging whether or not a resolution of the image data decoded in said
step (b) is higher than a resolution of the display device in said step
(d) to display the image on the basis of the image data; and
(f) controlling said step (d) to cause the display device to display the
image based on the image data multilevel-generation processed in said step
(c) if YES in said step (e), and said step (d) to cause the display device
to display the image based on the binary image data decoded in said step
(b) if NO in said step (e).
13. A computer readable program, stored in a storage medium, for performing
an image processing method comprising the steps of:
(a) reading out hierarchically encoded binary image data stored in a
storage medium;
(b) sequentially decoding the binary image data read out in said step (a),
in the order of a low-resolution image to a high-resolution image;
(c) judging whether or not a resolution of the image decoded in said step
(b) exceeds a predetermined resolution;
(d) performing a multilevel generation to the binary image data decoded in
said step (b);
(e) causing a display device to display the image, on the basis of the
image data decoded in said step (b) or the image data
multilevel-generation processed in said step (d); and
(f) controlling said step (e) to cause the display device to display the
image based on the image data multilevel-generation processed in said step
(d) if YES in said step (c), and said step (e) to cause the display device
to display the image based on the binary image data decoded in said step
(b) if NO in said step (c).
14. A computer readable program, stored in a storage medium, for performing
an image processing method comprising the steps of:
(a) reading out hierarchically encoded binary image data stored in a
storage medium;
(b) sequentially decoding the binary image data read out in said step (a),
in the order of a low-resolution image to a high-resolution image;
(c) sequentially switching the image decoded in said step (b) to cause a
display device to display the switched image;
(d) inputting an interruption instruction of the image switching to be
displayed in said step (c);
(e) performing a multilevel generation to the binary image data decoded in
said step (b); and
(f) controlling, in accordance with input timing of the interruption
instruction in said step (d), the switching in said step (c) between the
operation of causing the display device to display the image based on the
binary image data decoded in said step (b) or the operation of causing the
display device to display the image based on the image data
multilevel-generation processed in said (e).
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing method, and more
particularly to an image processing method when image data stored in a
storing medium is output.
2. Related Background Art
Hitherto, a filing system is known which stores in a storing medium plural
image data as a file together with keywords for searching the image data,
searches the stored image data by inputting the keyword or the like,
displays the image data on a display device, and prints out the image data
by a printer. In this type of system, a resolution of the printer is
usually higher than that of the display device. Thus, the image data is
stored in the storing medium at the resolution suitable for the printer.
However, if the stored image data is to be displayed on the display
device, the image data is thinned out such that the resolution of the
image data coincides with that of the display device, whereby a serious
problem occurs where image quality is deteriorated due to such thinning
process.
SUMMARY OF THE INVENTION
The present invention is applied in consideration of the above-mentioned
problem and an object thereof is to prevent the serious deterioration of
an image when image data stored in a storing medium is output.
Another object of the present invention is to enable to quickly search
image data stored in a storing medium.
Still another object of the present invention is to enable to utilize a
general display device.
The above-mentioned objects of the present invention and other objects will
become apparent from the following detailed description based on the
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the structure of an image processing
apparatus according to an embodiment of the present invention;
FIG. 2 is a view for describing a hierarchicality of an image to be stored
in a hard disk;
FIG. 3 is a view for describing a multi-level generation process for a
binary image;
FIG. 4 is a flow chart for describing a procedure of a process when an
image stored in a hard disk is displayed; and
FIG. 5 is a view for describing another example of a multi-level generation
process of a binary image.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the present invention is described in detail below with
reference to the drawings.
FIG. 1 is a block diagram showing an outline of the structure of an image
processing apparatus according to the present invention.
In FIG. 1, a memory 101 is composed of a read only memory (ROM) which
stores a program for controlling the image processing apparatus and a
random access memory (RAM) which is used as a work area. A scanner 102
reads an original image with a resolution of 400 DPI.times.400 DPI for
obtaining monochrome binary image data. A printer 103 prints a one-pixel
binary image (the binary image for one pixel) in monochrome with the
resolution of 400 DPI.times.400 DPI. A display 104 has a displaying
capacity of 8-bit and 256-gradation for each of R, G and B colors.
However, in this embodiment, an example for treating a monochrome image is
described. In this case, a monochrome image is displayed by switching a
pixel size in accordance with the gradation number of one pixel of image
data. That is, an image is displayed in such manner as an image is
represented by ON or OFF of a dot if binary, and an image is represented
with five stages per one pixel depending on OFF of a dot or the four
stages of pixel size if 5-level. A CPU 105 controls the entire image
processing apparatus on the basis of the program stored in the memory 101.
An encoder 106 compressively encodes image data to perform a hierarchical
encoding (an encoding for each of plural resolutions) of binary image
data. Concretely, an encoding of a known JBIG system is performed. A
decoder 107 expansively decodes image data to execute a process for
returning the compressive-encoded data as mentioned above to original
image data. At this time, image data of the most coarse resolution is
first decoded to output it after performing a scaling for coinciding it
with the resolution of the display 104, and then, the resolution is
sequentially caused to be increased. Ordinary, the resolution is slowly
increased responding to passing of time. However, by designating the
resolution, the image data can be output with the designated resolution. A
multi-level generation unit 108 converts one-pixel binary image data into
one-pixel multi-level image data and executes a process for decreasing the
resolution (the number of pixels) of the binary image data to increase the
number of gradations per one pixel. A hard disk 109 stores the compressed
image data. There is provided a key board 110 to which searching
information, various commands or the like are input by an operator. The
above-mentioned parts are connected to each other by a system bus.
FIG. 2 is a view for describing a hierarchicality of an image. An image
which is read by the scanner 102 or an image to be output by the printer
103 is a binary image with the resolution of 400 DPI indicated by a
reference numeral 206. When this data is compressed in the JBIG system by
designating 5-layer (an image of the most coarse resolution is encoded,
and then difference data for each resolution is encoded) to expand the
resulted data, an image of 0th layer indicated by a reference numeral 201
is initially obtained. In this example, since an initial original image
indicates the resolution of 400 DPI, the resolution of an image of the
most coarse resolution corresponds to 12.5 DPI. Upon executing an
expansion process responding to the passing of time, the image is expanded
to an image with a resolution of 25 DPI of a first layer indicated by a
reference numeral 202. Then, the image is expanded to an image with a
resolution of 50 DPI of a second layer indicated by a reference numeral
203, and expanded to an image with a resolution of 100 DPI of a third
layer indicated by a reference numeral 204, and further expanded to an
image with a resolution of 200 DPI of a fourth layer indicated by a
reference numeral 205. Finally, the image is expanded to an image with a
resolution of 400 DPI of a fifth layer indicated by a reference numeral
206. This is the same as the original image. In this embodiment, the image
of the fourth layer indicated by the reference numeral 205 is multi-level
processed to convert it into an image (207) which is 5-level processed
with a resolution of 100 DPI as indicated by the reference numeral 207 for
displaying it. Further, the image of the fifth layer indicated by the
reference numeral 206 is multi-level processed to convert it into an image
which is 17-level processed with a resolution of 100 DPI as indicated by a
reference numeral 208 for displaying it.
In case where a searching is sequentially performed with displaying the
image, a user can quickly obtain an outline of image at first by the data
having the hierarchicality depending on the resolution. That is, since an
image having a high resolution can be gradually obtained, in a case where
the searching is performed while observing the image, a process for
needlessly expanding an excellent image is omitted by interrupting a
process for expanding an image which has a high resolution by instructing
a displaying of the next image, thereby enabling to improvement of an
operability. An excellent image can also be obtained by leaving the device
as is.
An excellent image can be obtained in proportion to increasing of the
resolution. However, an image can not be displayed at a resolution which
exceeds the resolution of the display 104. At this time, an image is
enlarged and displayed rather than the resolution being increased. That
is, a detailed portion can be accurately visualized, but an entire image
becomes inaccurate. Therefore, when the resolution reaches that of the
display 104, it is possible to execute a process for displaying an image
by interrupting an expansion operation. However, in order to display the
more excellent (high quality) image, an image is displayed in the binary
form (only ON or OFF of a dot) as is until the resolution reaches that of
the display 104, and an image is displayed by converting information of
the resolution into information of the gradation when the resolution
exceeds that of the display 104, in a case where the image which is formed
corresponding to the resolution of the scanner 102 or the printer 103 is
displayed at the resolution of the display 104.
FIG. 3 is a view showing an example of a multi-level generation process to
binary image which process represents a conversion process of the
resolution information into gradation information. A reference numeral 301
denotes a state of a binary pixel having a resolution 200 DPI. In the
state 301, each pixel has a value of 0 or 1, and the value is multi-level
processed to obtain a one-pixel 5-level image having a resolution of 100
DPI shown in a state 302. In this example, with respect to one pixel of
the state 302 belonging to the same position as that of four pixels in the
state 301, the values of pixels in the state 301 are summed such that an
obtained value is set to be a pixel value in the state 302 as is. Since
each of the four pixels in the state 301 is expressed by a combination of
0 and 1 and therefor can obtain four kinds of values 0 to 4, the one-pixel
5-level image is obtained in the state 302. A state 303 represents an
example of binary pixels having 400 DPI.
Similarly, with respect to one pixel of the state 304 belonging to the same
position as that of 4.times.4 pixels in the state 303, the values of
pixels in the state 303 are summed and then multi-level processed, so that
17-level image (0 to 16) is obtained in the state 304.
The display 104 in the present embodiment displays data having gradation by
converting it into 8-bit 156-gradation data. Thus, scaling for converting
5-stage data into 255-stage data or converting 17-stage data into
255-stage data is performed.
That is, in one-pixel binary case, data of 0 and 1 are converted into 0 and
255 respectively, in one-pixel 5-level case, data of 0, 1, 2, 3 and 4 are
converted into 0, 63, 127, 191 and 255 respectively, in one-pixel 17-level
case, data of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16
are converted into 0, 15, 25 31, 47, 63, 79, 95, 111, 127, 143, 159, 175,
191, 207, 223, 239 and 255 respectively.
FIG. 4 is a flow chart showing a displaying process of the present
embodiment. This flow chart is based on a program stored in the memory 101
and is controlled by the CPU 105. However, the same operation can be
performed even if this program is stored in a detachable memory such as a
floppy disk or the like and then loaded by another device.
At first, when a search is started for an image stored in the hard disk 109
as a file by inputting key words or the like from the keyboard 110,
compressive encoding data of a corresponded image is selected for starting
the displaying process (step 401). The hard disk 109 stores image data
such that it can be output until the resolution of 400 DPI.times.400 DPI
corresponding to the resolutions of the scanner 102 and the printer 103.
In a step 402, compressive encoding data of a 12.5 DPI image which is an
initial layer of the image selected in the searching process is read out.
Then, in a step 403, it is discriminated whether an interruption of the
displaying process is instructed. In this case, the interruption is made
by instructing from the keyboard 110 to interrupt the displaying process
if the present displaying state is sufficient for image confirmation, or
by interrupting the displaying process of the presently-processed image
with instructing to display a next image. In this operation, if the
interruption instruction is input, the processing is terminated while
leaving the present display state as is (a step 409). On the other hand,
if it is instructed to display the next image, the processing again starts
in the step 401. If it is not interrupted, the flow advances to a step 404
to judge whether the processing is terminated until the final layer. If
the processing is terminated until the final layer, the entire processing
is also terminated. If not in the step 404, the flow advances to a step
405 to decode the compressive encoding data read in the step 402. Then, in
a step 406, it is judged whether the presently-decoded image reaches a
layer to which multi-level generation displaying is to be performed (i.e.,
the resolution of the image exceeds that of the display 104). Here, it is
assumed that the resolution of the display 104 has been preset and stored
in the memory 101. That is, in the present embodiment, it is judged
whether the image is equal to or more than a fourth layer. If it is judged
that the image is the fourth or fifth layer, the flow advances to a step
407 to perform the multi-level generation processing as mentioned above.
In a step 408, the image is displayed on the display 104 on the basis of
the decoded data. Thereafter, the flow repeats the processing until it is
judged that the processing of the final layer is terminated in the step
404 or it is instructed to interrupt the processing in the step 403. In
other words, the difference data from the presently-displayed image is
read in the step 402, and decoded in the step 405. Then, the decoded data
is converted into the multi-level data if the multi-level generation
processing is needed, and the presently-displayed image is rewritten and
sequentially displayed in the step 408.
In the multi-level generation processing of the above embodiment, the
multi-level is simply set to correspond to the number of density level "1"
of the pixel in the high-resolution image corresponding to the target
pixel of the low-resolution image. However, in order to preserve an edge
component, a window processing may be performed in which weighting
coefficients 502 are multiplied to 4.times.4 pixels 501 and values of the
all pixels are summed, as shown in FIG. 5.
Further, if the resolution of the scanner is greatly different from that of
the display, e.g., 1200 DPI for the scanner and 60 DPI for the display, an
upper-limit resolution for multi-level generation displaying may be set so
as to inhibit the processing for the portion from which a high image
quality can not be obtained even if the multi-level generation is
performed. For example, this type of processing can be performed by
judgment as to the layer to be multi-level generation displayed, instead
of a judgment as to the final layer in the step 404 of FIG. 4. Namely, it
can be performed by terminating the processing if it is judged that the
processing reaches the layer to be multi-level generation displayed. In
addition, it can be performed by previously designating the resolution and
terminating the display processing at the time when the displaying is
performed based on the previously-designated resolution.
In the above embodiment, a case of treating a monochrome image is
described. However, even if a color image is treated, the same processing
can be performed. In such a case, the above processing is performed for
each of the three color (R, G and B) data.
As described above, according to the present invention, the input image
data is hierarchical encoded as data having a different-resolution layer
structure and then is stored in the storing medium (i.e., hard disk) as
the file. In this operation, in a case where a stored image is searched to
be displayed on the display 104, the low-resolution image is first
expanded and displayed, and then the high-resolution image is gradually
displayed. Accordingly, the image to be first displayed can be displayed
at a high speed, so that an operator can quickly search and recognize the
image. Further, data whose resolution exceeds that of the display is
converted into one-pixel multi-level data, so that a high-quality image
can effectively be obtained. As a result, visualization of a character
image can be especially improved.
Moreover, there is no need to make the resolution of the display high such
that it coincides with that of the scanner and the printer, so that a
low-cost general-purpose display can be used. It should be noted that the
storing medium for storing the image data may be a detachable type such as
an optical magnetic disk or the like.
The present invention is described above on the basis of the preferred
embodiments. However, the present invention is not limited to such, and
can be modified in various manners within the scope of following claims.
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